COLLAGEN CROSS-LINKS IN FIBROMYALGIA

Objective. To determine if abnormal collagen metabolism is a character istic of fibromyalgia. Methods. The diagnosis of fibromyalgia,vas made according to the American College of Rheumatology criteria. Skin biop sy samples were obtained from the trapezius region of 8 patients with fibromyalgia, Urine was collected under standardized conditions from 5 5 control subjects and 39 patients with fibromyalgia, and serum was ob tained from 17 controls and 22 patients with fibromyalgia. Pyridinolin e (Pyd), an indicator of connective tissue disease, and deoxypyridinol ine (Dpyd), an indicator of bone degradation, both of which represent products of lysyl oxidase-mediated crosslinking in collagen, were anal yzed by ion-paired and gradient high-performance liquid chromatography (HPLC) methods with fluorescence detection. Levels of hydroxyproline (Hyp), a collagen turnover marker, were also measured. The findings we re related to creatinine levels, and the Pyd:Dpyd ratio was determined . Results. Highly ordered cuffs of collagen were observed around the t erminal nerve fibers by electron microscopic examination of biopsy tis sue from all 8 patients with fibromyalgia, but were not observed in an y of the control skin samples, The Pyd:Dpyd ratios in the urine and se rum and the Hyp levels in the urine were significantly lower in patien ts with fibromyalgia than in healthy controls. Conclusion. Decreased l evels of collagen crosslinking in fibromyalgia may contribute to remod eling of the extracellular matrix and collagen deposition around the n erve fibers, and may contribute to the lower pain threshold at the ten der points, Analysis of altered collagen metabolism either by histolog ic examination on biopsy, or preferably, by HPLC analysis of collagen metabolites in urine or serum may aid in understanding more about the pathogenesis of fibromyalgia.